ZMAX Long-Life high-low threads and sharp cut point allows for holding power. ZMAX can be used with battery operated and impact screw guns. ZMAX alloy fasteners are engineered for corrosion applications. ZMAX offers a large outer diameter to prevent wind uplift and is suitable in snow load regions. The ZMAX Long-Life is ideal for coastal environments, preventing red rust on fastener heads once installed into metal buildings.

“Improving Wind Uplift on Metal Roofs” is a new AIA continuing education course, developed by S-5! and MBCI to help architects discover the art and science of wind control and wind uplift on metal roofs and metal structures.

This is a one hour AIA Health, Safety and Welfare (HSW) learning unit course. It offers architects the opportunity to learn about wind uplift requirements, testing and proper wind mitigation specification techniques as well as metal roof options and accessories to improve wind uplift characteristics.

Architects and firms requesting a presentation of this course will learn about:

The proper selection and specification techniques of wind-rated roofs and accessories to meet uplift requirements

Keith Lipps, vice president of sales and marketing for S-5!, described the course as being critical for design professionals to understand how wind forces act on a structure. “This is a critical topic for projects being designed in high wind areas, especially those structures that are being built in tornado and hurricane prone regions,” Lipps says.

The course can be scheduled as a live presentation through S-5!. Call 1-888-825-3432 or email info@s-5.com for more information.

Elementary school students sometimes find themselves staring out the window, but few have a view to rival that of the students at Sullivan’s Island Elementary School in Sullivan’s Island, S.C. The school is located on oceanfront property, and when it was time for the original building to be rebuilt, the site posed numerous challenges.

The standing-seam roof is made up of 0.040-inch coated aluminum panels that are 18-inches wide.

The original school had been built in the 1950s. It had been designed for 350 students and built on grade. The new school would have to be elevated to conform to modern building codes and service 500 students. The structure would not only have to withstand high winds, severe weather and a salt-air environment, but it also would have to fit into its surroundings. Many residents feared the larger building would look out of place in the cozy beach community. It was architect Jerry English’s job to figure out a way to make it work.

English is a principal at Cummings & McCrady Architects, Charleston, S.C., the architect of record on the project. He worked with a talented team of construction professionals, including Ricky Simmons, general manager of Keating Roofing & Sheet Metal Co. Inc. in Charleston, to refine his vision and bring it to life. English and Simmons shared their insight on the project, and they both point to the building’s metal roof as a key element in the project’s success.

CHALLENGING DESIGN

Cummings & McCrady Architects handles a broad range of commercial, institutional, religious and historic work—new construction and renovation. The firm had done a lot of work with the Charleston County School District over the years, including a small library addition for the original Sullivan’s Island Elementary School after Hurricane Hugo passed through in 1989, and it was awarded the new construction project.

The building’s foundation system had to meet strict regulations regarding resistance to storm surge. The building is elevated on concrete piers, which were topped with a 6-inch reinforced concrete slab. Metal framing was constructed above the slab. “With our building, we had to raise the underside of the structure almost 7 feet above the grade,” English recalls. “What we did is we built it a little bit higher than that so the underside could be left open and used for playground.”

For English, coming up with a design that would reflect the character of the local community was the biggest challenge. To achieve that goal, he broke up the building into four sections and spread them across the site with the tallest sections in the center. “We have four linked segments that transition down on each end to the height of the adjacent residences,” he says.

The roof was also designed to blend in with the neighboring homes, many of which feature metal roofs. “The idea of pitched roofs with overhangs became a strong unifying element,” English explains.

English checked with several major metal roofing manufacturers to determine which products could withstand the harsh oceanfront environment and wind-uplift requirements. “Virtually every one of them would only warranty aluminum roofing,” he says. “The wind requirement and the resistance to the salt air were what drove us to a coated aluminum roof.”

The majority of the panels were factory-made, but Petersen Aluminum supplied the rollforming machine and the operator to handle the onsite rollforming of the largest panels.

The standing-seam roof is made up of 0.040-inch coated aluminum panels that are 18-inches wide. Metal trusses give the roof system its shape. English tapped the resources of roof consultant ADC in Charleston and the metal roofing manufacturer to iron out all the details. English wanted to avoid any cross seams in the metal roofing, so he worked with Dave Landis, the manufacturer’s architectural/technical sales manager, to arrange for the longest panels to be formed onsite.

The roof also includes two decks that serve as outdoor teaching areas. These sections were covered with a two-ply modified bitumen roof system and protected with a multi-colored elevated concrete paver system.

Another standout feature is the school’s entry tower, which is topped by a freestanding hip roof featuring curved panels. This roof was constructed with panels that were 12-inches wide. “We found other examples on the island where the base of the roof flares a little bit as a traditional element, and with the closer seamed panels they were able to get those curves,” English says. “It’s a refinement that’s a little different than the rest of the roof, but it’s the proper scale and the fine detailing pulls it together and sets if off from the main roof forms that are behind it.”

UL 580 is the Standard for Tests for Uplift Resistance of Roof Assemblies. Roof assemblies are tested for their ability to resist both external and internal pressures associated with high velocity winds.

RidgeLine is a patented 2-3/8-inch tall mechanically seamed roofing panel covering 42 inches, with thickness options of 2.5, 3, 4, 5 and 6 inches. The core is a continuously poured-in-place, polyisocyanurate insulating foam. Exterior and interior metal panels are available in 26-, 24- and 22-gauge Galvalume steel. Exterior finish is standard gloss PVDF coating. RidgeLine panels can be used on slopes as low as 1/2:12 and are available in standard lengths measuring 12 to 53 feet, with custom lengths available on demand. Green Span Profile’s UL construction number is 698.

Tectura’s Lok Down system is a proprietary pedestal system for rooftop pavers. A top plate, made to match or contrast with the pavers, fits into a recess, allowing for a flush walking surface. Colored bolts then tighten the system together for a total rafted paving system. Lok Down is the only system backed by full-scale tests that simulate the effects hurricane conditions on rooftop paving products. The Lok Down system is tested to withstand wind speeds of more than 145 mph.

Hundreds of people milled about the terminals at Lambert-St. Louis International Airport on the evening of April 22, 2011. Three airplanes with passengers on board sat on the tarmac. It was business as usual at one of the largest municipal airports in the country. But meteorological conditions were anything but usual. A powerful supercell over St. Louis spawned an EF4 tornado (view the Enhanced Fujita Scale, which rates the strength of tornados by the damage caused, on page 2) packing 150-mph winds. The twister barreled directly into the airport 11 miles northwest of downtown, blowing out half the floor-to-ceiling windows in the main terminal and inflicting approximately $30 million in damages. In addition, the tornado seriously damaged part of the copper roof over Terminal 1.

CopperPlus was installed in stages over the domes at Lambert-St. Louis International Airport. Like solid copper, copper-clad stainless steel acquires a patina over time.

The 55-year-old roof was iconic and beautiful. Its four copper domes had been the crowning glory of Lambert-St. Louis International Airport, welcoming up to 13 million international passengers each year. But the roof had been showing its age for some time, leaking often and requiring frequent maintenance. Following the tornado strike, airport officials made the difficult decision to permanently retire the roof. “The tornado damaged less than 10 percent of the total roof, but that section needed to be totally replaced,” explains Jerry Beckmann, deputy airport director of Planning & Development. “That damage, plus the fact that the roof was almost 60-years old, influenced our decision.”

Airport officials were challenged to install more than 100,000 square feet of material over four domed vaults as quickly as possible with minimal disruption to the public. Beckmann, who is an engineer, wanted a roof that was watertight and capable of withstanding high winds while airport administrators wanted to maintain the roof’s mid-century architectural integrity. All parties wanted the project completed as economically as possible with results that were aesthetically pleasing, historically appropriate and, most important, built for harsh weather events.

COPPER AND STEEL

They found the solution in copper-clad stainless steel, a material that has been used in roofing applications for roughly 50 years. The selected ASTM B506-09 architectural metal features two outer layers of 100 percent copper strip roll bonded at very high pressures to a core of Type 430 stainless steel, the same metallurgical bonding process used to make U.S. quarters and dimes. The material delivered the natural beauty and patination properties of solid copper with the strength and durability of stainless steel—exactly the attributes desired by officials at Lambert-St. Louis International Airport.

“Copper-clad stainless steel is a great-looking material that can be fabricated for any roofing style. You can’t tell the difference between it and straight-up copper,” says Shane Williams, vice president of Civil Construction for Kozeny-Wagner Inc., the Arnold, Mo.-based general contractor awarded the public bid by the city of St. Louis. “It’s stronger, has a better shelf life and costs less than pure copper. This allowed us to bid competitively for the job and even return a credit to the city of St. Louis.”

Workers install CopperPlus batten-seam panels over a dome at Lambert-St. Louis International Airport. Step-by-step, the installation of CopperPlus is virtually identical to that of copper.

The owners of Missouri Builders Service Inc., the Jefferson, Mo.-based roofing subcontractor, were attracted to the material’s lighter weight and easy solderability. “We were going to have to maneuver a lot of material on the job site and perform a very large amount of soldering to cover four domes,” notes John Kinkade, Missouri Builders Service’s vice president. “We liked that copper-clad stainless steel had a lower thermal conductivity for easier soldering. That was important to us, given the scope of the project.”

The $6.7 million project to replace the airport roof was announced at a press conference in March 2014 by St. Louis Mayor Francis Slay, St. Louis County Executive Charlie Dooley and Lambert-St. Louis International Airport Director Rhonda Hamm-Niebruegge. “The new skin will shine of raw copper like it did in the mid ’50s when the terminal was built,” Slay stated in a press release issued by the airport. “The roof will slowly transform in color again in time as this airport serves new generations in this region.”

WEATHERING NATURE’S WORST

Copper-clad stainless steel has become more popular in tornado and hurricane-prone regions of the U.S. in recent years, thanks to the strengthening of building codes for wind-lift and hail-resistance standards. Copper-clad stainless steel conforms to Miami-Dade BCCO requirements and exceeds UL2218 Class 4 hail-test requirements; wind-uplift tests have shown its strength to be equivalent to steel at the same gauge. It offers a strength advantage compared to solid copper, providing higher tensile strength and yield strength at a thinner gauge than monolithic copper.

Numerous churches, college buildings, museums, private residences and other buildings nationwide now feature copper-clad stainless steel in their custom roofs, dormers, cupolas, flashings and downspouts. Notable installations include the following:

Several 67-foot panels of copper-clad stainless steel were rolled onsite, then lifted and put in place by a crane to replace the ice-damaged roof at the St. Francis of Assisi Catholic Church, Traverse City, Mich.

In 2012, more than 30,000 square feet of copper-clad stainless steel were installed in the fascia and coping of the Trinka Davis Veterans Village, Carrollton, Ga., the nation’s first privately funded U.S. Department of Veterans Affairs’ VA facility.

In 2014, the material was selected for a 2,100-square-foot perforated sunscreen installation in San Francisco’s Mission Bay neighborhood, one of the most significant urban development projects in the U.S.

PHOTOS: MISSOURI BUILDERS SERVICE INC. AND LAMBERT-ST. LOUIS INTERNATIONAL AIRPORT

On the night of May 4, 2007, brothers Kelly and Mike Estes saw their BTI-Greensburg John Deere Dealership obliterated by an EF5 tornado nearly 2-miles wide (according to the Enhanced Fujita Scale, which rates the strength of tornados by the damage caused; view the scale on page 3). Astoundingly, 95 percent of their town—Greensburg, Kan.—was also destroyed that day. The tornado did much more than rip roofs off buildings and toss things around; it turned the entire community into what looked like kindling.

Rarely do communities get hit by an EF5 tornado, which can come about when air masses collide. Sometimes warm, humid air from the Gulf of Mexico rises above drier air from the Southwest deserts in the U.S. This can create unstable conditions resulting in thunderstorms and worse. A strong collision of air masses creates a strong storm. Additionally, wind patterns and the jet stream can magnify the storm, resulting in what people refer to as “the perfect storm”.

After being completely destroyed by an EF5 tornado, the BTI-Greensburg John Deere Dealership has been rebuilt in Greensburg, Kan., in a better, greener way.

Despite the large-scale losses incurred by the entire town, 100 customers and friends of the Estes family showed up the morning of May 5 to help them salvage what remained of their business. Shortly after the tornado disaster, Kansas Gov. Kathleen Sebelius stated her wish that Greensburg become the “the greenest city in the state”.

As part of their commitment to their community, Kelly, Mike and their family decided to rebuild their business in a better, greener way. They wanted the new 28,000-square-foot prefabricated metal building to be the world’s greenest farm-machinery facility; attain a LEED Platinum rating from the Washington, D.C.-based U.S. Green Building Council; and use the least energy possible. One of the most important considerations was using building materials that could withstand future tornados.

DAYLIGHTING

To help achieve LEED Platinum and outlast any future high-velocity winds, they incorporated 12 Daylighting Systems in their retail area’s roof to showcase their merchandise; reduce lighting energy costs; and flood the area with natural light, a benefit for customers and employees.

The Daylighting Systems capture light through a dome on the roof and channel it down through a highly reflective tube. This tubing is more efficient than a traditional drywall skylight shaft, which can lose over half of the potential light. The tubing fits between rafters and installs with no structural modification. At the ceiling level, a diffuser that resembles a recessed light fixture spreads the light evenly throughout the room.

The dome is made from high-quality acrylic resin that is specifically formulated for increased impact strength, chemical- and weather-resistance, and high clarity (a polycarbonate inner dome is used for high-velocity hurricane zones). Domes are engineered to deflect midday heat and maximize low-angle light capture. The tubing is made from puncture-proof aluminum sheet coated with the highly reflective material for maximum light transfer. The units (independently tested by Architectural Testing in Fresno, Calif.) comply with various building codes including the 2009 International Building Code and 2010 Florida Building Code, including high-velocity hurricane zones.

“When our power went out one time for four hours, we were able to keep the shop open and operating due to daylight strategies, which includes the Daylighting Systems,” notes Mike Estes. “We didn’t anticipate this benefit but we’re really happy to have this bonus.”PHOTO: SOLATUBE INTERNATIONAL INC.

Wind damage to roof systems is often catastrophic, placing the building users at a life-safety risk, resulting in interior and furnishing damage and suspension of interior operations, loss of revenues, legal ramifications and great costs to repair. Because of my 30 years of experience in the design of roof systems and forensic investigation, I’m often called upon as an expert witness after wind events. In this article, I’ll review a couple wind-event roof failures, the causes of the failures and how they could have been prevented. I’ll also provide recommendations for failure prevention in the design process for new roof systems, as well as for existing roof systems.

1. The concrete roof deck panels deflected more than 3/4 inch, which the design architect should have accounted for if a thorough field investigationwas undertaken.

The Perfect Storm

How can it be that when roof systems are to be designed for code-required wind-uplift resistance that so many fail in winds well below the design parameters and/or warranty coverage? The answer could be design-related, material or installation; typically, it involves all three.

Architects and some roof system designers are often not as knowledgeable about roof systems as they should be, have little empirical evidence in how all the components work together as a system, and move beyond their abilities (a violation of their standard of care) when designing roofs where specific detailing is required. In addition, manufacturers are all too often
bringing new products to the marketplace that have not been properly vetted in the field and their long-term performance is truly unknown. Unfortunately, the roofing contractor cannot escape any of this. The lack of proper specification and contract document review; failure to review product data, including installation guidelines for new products; poor project oversight and management; and pressure from general contractors often result in installations that are subpar. The result is a “perfect storm” of design, materials and installation that fail under stress.

Consider the following case studies that I have been involved in as a forensic or “expert” witness when litigation was involved.

Coastal Facility

A large aged warehouse along the eastern seaboard was in need of a new roof system. Because the interior was not conditioned, thermal insulation was not required. The existing roof was an asphalt built-up with aggregate surfacing on high-density fiberboard on precast concrete panels 24-inches wide on a steel structure. The northern portion of the building had overhead doors that were seldom closed. On the interior, an aedicule structure (a building within a building) was constructed approximately 65-feet south of the overhead door, which had a ceiling level 5-feet below the roof deck.

2. The thin, flexible 1/2-inch-thick high-density board was found to have little, if any, contact with the full-coverage spray-foam adhesive, making uplift extremely easy.

The architect who designed the replacement roof system called for the existing BUR roof to be removed down to the precast concrete roof panels. Then a new 1/2-inch 4- by 8-foot high-density wood fiberboard was set in full-coverage spray polyurethane foam adhesive with a 60-mil EPDM membrane fully adhered to the high-density wood fiberboard.

Additionally, the architectural drawings called for rooftop relief vents to be removed and capped over.

Around June 2008, a Nor’easter (an intense rainstorm), coming in from the east off the ocean, swept into the city. This resulted in the new roof system being lifted off the roof deck. Mode of failure was the fiberboard detaching from the precast concrete roof deck.

Investigation revealed several acts and conditions that contributed to the wind damage.

This morning I awoke to our first real snowfall of the season—about 7 inches. I typically enjoy watching the snow flutter down, but as it fell yesterday afternoon into the night I began to dread shoveling my long driveway. As I was brewing my coffee this morning, I heard a motor outside my window and spotted my next-door neighbor walking up and down my driveway behind his snow blower. I immediately went outside to thank him. I plan to bake him cookies today and offer him gas for his snow blower to show my gratitude. And, in the future, if he needs me to walk his dog or check his mail when he’s away, I’m more than willing.

My neighbor’s kindness reminded me of this issue of the magazine. The concept of “having someone else’s back” came up again and again as I edited the contributed articles. For example, our editorial advisory board member Thomas W. Hutchinson, AIA, FRCI, RRC, CSI, RRP, principal of Hutchinson Design Group Ltd., Barrington, Ill., writes in his regular series, “From the Hutchinson Files”, about how communication and collaboration between roof system designers, installers and manufacturers will lead to roofs that withstand high-wind events. He shares two examples of roof system failures that he notes would not have occurred if all parties had collaborated—and taken care in their work.

You can read an example of extreme collaboration in this issue’s “Tech Point”. Contributor KJ Fields describes the reroofing of the 10.3-acre James W. Jardine Water Filtration Plant in Chicago. Not only did Chicago-based Trinity Roofing Service’s crews have to contend with a phased schedule to ensure the plant continued to supply fresh water to its 5 million customers, but they also dealt with roof-load restrictions, unique stainless- steel expansion joints, the Department of Homeland Security and Chicago’s wild weather. Constant communication between Trinity Roofing Service and the membrane manufacturer, Flex, ensured a successful project.

If you’re looking for tips to ensure quality on your next roofing project, Richard Biosca, vice president of operations and general counsel for McHenry, Ill.-based Metalmaster Roofmaster, shares insight into his contracting company’s processes in “On My Mind”. The firm ensures quality as early as the pre-award, bidding and estimating phase of the project. Metalmaster Roofmaster’s estimators, submittal department, project managers, crews and service department are encouraged to discuss and address issues and concerns. Biosca points out in his column, investing time and resources to collaborate all the way through a project has led to many returns for his company, including repeat customers, profitability and awards. Who doesn’t want that this year?

Installers of attachment systems on standing-seam metal roofs (SSMR) can now rest assured their roofs will resist wind uplift and seismic vibration with the A2 AceClamp. The A2 AceClamp’s unique design virtually eliminates the need for periodically re-torquing clamps to preserve manufacturers’ warranties, as is recommended for other SSMR clamp systems.

The A2’s innovative solution prevents torque back-out, caused by wind flutter or constant seismic vibration, by employing a distinctive “push-pin” design that locks two stainless steel pins into the roof panel to secure the clamp. The design effectively prevents loosening or torque back-out and is Patent-Applied-For.

Prior to the A2, manufacturers relied on round or concaved-headed set-screws that turned and rotated into the metal roof’s surface to penetrate and lock into the metal seam. This typically resulted in scratches or damage to the panels’ surface. The A2’s sliding push-pin design eliminates this concern. The A2 solution does not damage or scratch the panel surfaces, thus upholding manufacturers’ warranties while assuring one of the strongest clamp systems in the industry.

For solar-racking installations, the A2 saves time and additional costs where grounding cable brackets are used. The A2 is designed with a grounding cable groove in the clamp. A stainless-steel sleeve and set-screw kit securely hold the grounding wire in place. For the installer, this feature eliminates the need for a separate grounding attachment, as the cable groove is incorporated into the clamp itself. The stainless steel sleeve also prevents corrosion of the grounding wire while enhancing electrical conductivity.

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March/April 2019

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About Roofing

Roofing is a national publication that unravels, investigates and analyzes how to properly design, install and maintain a roof system. Through the voices of professionals in the field, Roofing’s editorial provides a unique perspective.